May I ask why you recommend changing the spare even if I go with 17s?
The diameter will be identical so the only difference will be the offset.
I don't need to put 20K miles on them, I just need them to get me home.
Thanks
---------- Post added at 07:43 PM ---------- Previous post was at 07:30 PM ----------
Also, without wishing to sound like there's dune sand in my fajita ...
As much as I love Starbucks stereotypes, could anyone answer my actual question with some specifics as to what precisely I would be giving up in off road performance by using 20s instead of 17s?
20s have less sidewall. So less flex and less grip. More prone to puncture.
That said, there was a thread on here a while back on this where someone else asked the very same question (hint, hint... search) and some guys who actually send their shit off road (on 20s) chimed in. So you wouldn't be alone. But you would still be wrong.
Also, 20s will ride more rough on the road.
Plus you will look like a ******.
Just get the 17s man.